Short-Term Dynamics of Behavioral Thermoregulation by Adults of the GrasshopperMelanoplus sanguinipes

Abstract

The short-term behavioral responses of adult grasshoppers, Melanoplus sanguinipes (F.) (Orthoptera: Acrididae), were examined after they experienced changes in microclimate when beingforced to change positions in their habitat. It was also determined if and when behavioral tactics allowed adults to achieve body temperatures within their preferred range. The preferred or set-point range, here taken as the interquartile range of temperatures selected on a laboratory thermal gradient, was estimated to be 37.4–40.5°C. In the field, adults progressed through a relatively consistent daily sequence of behaviors, basking on the soil early in the day, but moving onto vegetation as temperatures increased. Although basking allowed grasshoppers to maximize body temperature within the available range, as much as 7°C in excess of air temperature, they could not attain preferred body temperatures until soil surface temperatures reach about 35°C. Basking was more effective in grazed than ungrazed pastures due to a lower degree of shading of the soil surface. As soil surface temperatures exceeded 35°C, grasshoppers could achieve body temperatures within the preferred range by moving to the appropriate height on vegetation. These results illustrate the advantage of assessing behavior in the field in relation to preferred body temperatures determined in the laboratory.

Effects of Abiotic Factors on the Geographic Distribution of Body Size Variation and Chromosomal Polymorphisms in Two Neotropical Grasshopper Species (Dichroplus: Melanoplinae: Acrididae)

“…In fact, in the case of endotherms for which the ecogeographic rules were originally formulated, a number of discrepancies occur and it is not always possible to explain the geographic body size trends by simple thermoregulatory models. This situation becomes more complex when trying to verify the rules in ectotherms that, in most cases, regulate body temperature behaviourally, as is the case of most studied Orthoptera [31][32][33][34][35].…”

The effectiveness of common thermo-regulatory behaviours in a cool temperate grasshopper

“…Although the behaviours we observed during the laboratory experiments (stilting, shade seeking, movement into the vertical position) are generally accepted as being common thermoregulatory behaviours in other grasshoppers (Anderson et al, 1979;Chappell, 1983;O'Neill and Rolston, 2007;Whitman, 1987), measurements of the resulting temperature changes are rare.…”

“…Gillis and Smeigh, 1987;Willott, 1997) relating them to the operative temperature of non-thermoregulating models (Hertz et al, 1993). Field studies on grasshoppers have demonstrated that the proportion of individuals exhibiting behaviours such as basking, stilting or crouching is related to surface temperatures (Chappell, 1983;Gilman et al, 2008;O'Neill and Rolston, 2007;Samietz et al, 2005), but few studies have attempted to measure the change in body temperature accompanying particular behaviours. Basking has been shown to lead to increases in body temperature under exposure to solar radiation, but the effects of passive warming and active thermoregulation are not always distinguished (Carruthers et al, 1992).…”

Effects of Solar Radiation on Animal Thermoregulation

“…Fire ants are able to raise their nest temperature by modifying their nest shape relative to the sun's angle, while wood ants use solar radiation in combination with behavioral modifications to maintain ideal nest temperatures (Vogt et al, 2008;Galle, 1973). Non-communal insects such as grasshoppers bask to increase their T B (O'Neill & Rolston, 2007). Butterflies in general often bask or use ground contact to gain heat by conduction and convection then seek shade or minimize their exposed wing surface area to either facilitate heat loss or decrease heat absorption (Clench, 1966).…”